Composition for application to a film for holding a food product

ABSTRACT

A coating composition for application to a food packaging film is disclosed. The resulting film can be used as a tubular food casing that, after cooking or heating, imparts a brown color to a foodstuff encased in the casing.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. provisional patent application 60/501,339, filed Sep. 8, 2003, and U.S. provisional patent application Ser. No. 60/454,444, filed Mar. 13, 2003.

FIELD OF THE INVENTION

[0002] The present invention relates to compositions for application to a film used as packaging material for a food product, and to food packaging films resulting therefrom. In particular, the present invention relates to compositions for application to a tubular food casing, and the resulting casing, that impart an esthetic brown color to a foodstuff when the foodstuff is cooked or otherwise heated within the casing.

BACKGROUND OF THE INVENTION

[0003] The use of food casings to encase a food-stuff prior to further processing, such as smoking, is well known. The traditional smoking process involves stuffing a foodstuff, such as a sausage, into a smoke-permeable casing, then hanging the stuffed food product in a smokehouse. In the smokehouse, wood is burned at low temperature to generate smoke. Smoking by such a traditional technique is labor intensive, time consuming (e.g., smoking times can span several days), and the amount of generated smoke often fails to comply with pollution laws.

[0004] In order to avoid difficulties associated with the use of smokehouses, packaged meat products have been placed in a heated smoke-free environment for cooking. The process of cooking a foodstuff in a casing by such a method is known as a “cook-in” process. Films for use in the “cook-in” process are referred to as “cook-in” films. However, foodstuffs cooked in this smoke-free manner do not acquire the characteristic brown surface and wood-smoked flavor of a smoked food product.

[0005] In order to provide the benefits of a smoked food product, but without the drawbacks of conventional smoking techniques, liquid smoke was developed decades ago. Liquid smoke is the aqueous condensate of a natural wood smoke, and contains phenols, acids, and carbonyl compounds, particularly aldehydes, that react with meat proteins and brown the meat surface. This browning gives the appearance of a naturally smoked food product.

[0006] Liquid smoke originally was atomized onto meat products encased in porous natural gut or cellulose casings prior to cooking in an oven. The porosity of the casings allowed the liquid smoke to penetrate the casing and into the meat. In practice, however, it was difficult to provide a uniform coating of the liquid smoke onto the food product by this atomization process.

[0007] In view of this difficulty, substantial research was directed to providing a substantially uniform distribution of liquid smoke on a food product surface. Some attempts were made to incorporate a liquid smoke into the meat product itself. However, this method either provided an insufficient amount of liquid smoke, and in turn browning, on the surface of the foodstuff or imparted an excessive smoky flavor to the food product.

[0008] A more successful approach has been to apply a liquid smoke onto a cellulose casing. Techniques for applying liquid smoke onto a cellulose casing include dipping or spraying a liquid smoke solution onto the cellulose casing, such that the liquid smoke on the interior surface of the casing can be transferred to an encased foodstuff. Such a treatment can present difficulties during further processing of the cellulose casings, and, in particular, can interfere with shirring. Despite these difficulties, a number of commercially available liquid smoke-treated cellulose casings exist commercially.

[0009] The permeability and porosity of cellulose casings makes them compatible for use with liquid smoke. However, these properties also introduce serious and widely recognized disadvantages. First, cellulose products are highly permeable to water vapor, which allows moisture loss during cooking and a corresponding decrease in overall weight of the product. A reduced yield of food product results, which is disadvantageous for commercial reasons. Further, cellulose casings are oxygen permeable, which leads to spoiling and/or discoloration of the food product. Because of this latter difficulty, food products cooked in cellulose casings either are consumed shortly after cooking or are removed from the casings, then rewrapped in an oxygen-impermeable barrier casing as quickly as possible after production. This rewrapping step provides an opportunity for contamination or infection of the food product, which represents a loss in quality and shortened shelf life. These additional steps also add to the cost of the food product.

[0010] To address the disadvantages of permeable cellulose casings, water and oxygen-impermeable thermoplastic casings were developed. When using a casing of this type, negligible weight loss occurs during the production process or during storage and shipping. Further, the food product remains sterile, provided the casing remains intact. However, as a result of the impermeability of the casing, smoke components in either gaseous or liquid form cannot penetrate the casing. Further, impregnation of thermoplastic casings with liquid smoke or other coloring additives has not been successful because thermoplastic casings do not adequately absorb and store impregnating agents. In order to impart a smoke color to thermoplastic-encased foodstuffs, it is necessary to remove the casing and apply an artificial color to the foodstuff, such as by spraying or dipping techniques, then repackage the foodstuff. These additional steps not only increase costs, but also increase the risk of food product contamination.

[0011] There is a recognized need in the art to provide a gas- and moisture-impermeable casing that can transfer browning and flavoring agents, such as a liquid smoke or other browning or flavor agent, to an encased foodstuff during cooking. However, to date, attempts to solve this problem and provide a commercially acceptable food product have failed for a variety of reasons. One approach was to blend a liquid smoke with a resin used for the inner layer of a plastic casing. This approach was unsuccessful for a number of reasons, including an insufficient transfer of the browning or flavoring agent to a meat surface, reaction and volatilization of the browning or flavoring agent at extrusion temperatures, and delamination induced by the presence of the browning or flavoring agent.

[0012] Another approach was to incorporate an absorbent browning or flavoring agent into the plastic casing. However, such a product has yet to be adopted commercially, and in practice it is believed that there is either an insufficient transfer of these agents from the casing to the foodstuff and/or insufficient retention of these agents on the surface of the casing.

[0013] A need still exists in the art for a composition that can be applied to a food packaging film in a sufficient amount to provide a desired golden brown color, and also being capable of transferring from the film to the foodstuff to provide the color.

SUMMARY OF THE INVENTION

[0014] The present invention is directed to compositions for application to a film used as a packaging material for a food product. The present invention also is directed to a food packaging film having a present composition applied to a food contact surface of the film. The composition is applied to a food contact surface of a food casing, and imparts an esthetic brown color to a foodstuff when the foodstuff is processed, i.e., cooked or otherwise heated, within the casing.

[0015] Therefore, one aspect of the present invention is to provide a composition for application to a film that can be used as a casing for a food product. The composition and treated film at least partially overcome the above-discussed disadvantages in browning a foodstuff, and provide a useful, commercial packaging material for a foodstuff.

[0016] Another aspect of the present invention is to provide compositions that can be applied to a film for use in encasing a foodstuff, and that effectively impart an esthetic brown color, and optionally flavor, to the cooked food product.

[0017] Still another aspect of the present invention is to provide a liquid composition for application to a food packaging film, said composition comprising:

[0018] (a) about 20% to about 47%, by weight, of a browning agent;

[0019] (b) about 0.05% to about 2%, by weight, of a viscosity-modifying agent;

[0020] (c) 0% to about 10%, by weight, of a surfactant, a polyol, or mixture thereof;

[0021] (d) 0% to about 3% of a pharmaceutically acceptable salt, e.g., sodium chloride; and

[0022] (e) water,

[0023] said composition having a pH of about 2 to about 6.5, and capable of transferring the browning agent of the composition from the food packaging film to a foodstuff packaged in the food packaging film.

[0024] These and other novel aspects of the present invention will become apparent from the following detailed description of the preferred embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] The present invention provides a film for use as a cook-in casing, wherein the film has a surface for contacting a packaged foodstuff. The film surface that contacts the foodstuff has a liquid composition of the present invention applied thereon. Typically, the composition permeates the film, but may remain, at least partially, on the surface of the film.

[0026] The composition comprises one or more browning agent, and an optional flavoring agent, for transfer to a packaged foodstuff. Prior to application of a present composition to the food contact surface of the film, the food contact surface preferably is subjected to a surface activation treatment.

[0027] The present invention relates to the surprising and unexpected discovery that a liquid composition of the present invention can be applied to an activated or unactivated surface of a casing, and the browning agent, and optional flavoring agent, can be effectively transferred to the encased foodstuff during heating or cooking. The composition effectively browns, and optionally flavors, the foodstuff to a consumer acceptable level.

[0028] In preferred embodiments, a present composition is applied to a film that has been surface activated prior to application of a present coating composition. The film activation process comprises subjecting a surface of the film to a surface activation treatment, then applying a sufficient amount of a liquid composition of the present invention to the activated surface to impart a predetermined brown color and, optionally, flavor level to a foodstuff encased by, and cooked in, the film.

[0029] The film can be prepared from any material suitable for packaging food and in which a food contained therein can be cooked or heated. Cook-in films can be single or multilayer films. Multilayer films include a food contact layer and one or more additional layers selected from sealant layers, abuse layers, bulk layers, oxygen barrier layers, moisture barrier layers, tie layers, and the like.

[0030] Persons skilled in the art are aware of suitable polymer materials and polymer blends for use in the construction of cook-in films. Typical polymer materials known in the art include, but are not limited to, polyolefins, such as polyethylene and higher alpha olefins, olefin copolymers with vinyl monomers, such as ethylene/vinyl acetate, ethylene/acrylic acid, or mixtures thereof. An especially preferred polymer material is a hydrophilic material, such as a polyamide.

[0031] Polyamides are known in the food packaging art, and include, but are not limited to, aliphatic polyamides, such as condensates of aliphatic primary diamines preferably having about 4 to about 8 carbon atoms, and aliphatic dicarboxylic acids preferably having about 4 to about 10 carbon atoms. An aliphatic copolyamide can be a homopolymer, or a polymer based on one or more aliphatic diamines and one or more aliphatic dicarboxylic acids and/or one or more omega-aminocarboxylic acids or omega-amino-carboxylic lactams. Examples of suitable dicarboxylic acids include, but are not limited to, adipic acid, azelaic acid, sebacic acid, and dodecane dicarboxylic acid.

[0032] The film also can include an additive to facilitate incorporation of a present coating composition onto or into the film. Suitable additives include, but are not limited to, water-soluble or water-swellable materials, such as a starch, a cellulose, e.g., alpha cellulose, a poly(ethylene oxide), a poly(vinyl alcohol), a polyacrylic acid, crosslinked polyvinylpyrrolidone (PVP), and copolymers or mixtures thereof. Preferred films contain PVP or a mixture thereof.

[0033] The polymer used to manufacture the film also can be blended with additives that promote melt fracture or modify flow. In some instances, processing additives are added to control melt fracture. The levels of these additives are judicially selected to provide the desired effect. Preferably, the film is heat-shrinkable under cook-in conditions such that the film conforms tightly to the cooked food product. Alternatively, the film can be shrunk prior to cooking by placing the package in a heated environment.

[0034] The surface of the film preferably is treated to increase the surface area of the film. Methods of surface treatment are known in the art and include ablation and etching. Alternatively, the surface can be roughened during extrusion by various methods, including extrusion through a roughened die or setting the melt and die temperatures to create a nonuniform or turbulent flow.

[0035] Typically, the film is in the form of a seamless tubular casing. Tubular casings are prepared by methods known in the art. Alternatively, the film can be formed as a single sheet, corona treated, coated with a composition of the present invention, and then formed into a tube by sealing the edges together. The process to form a single sheet into a tube by sealing is well known in the art as back seaming. Back-seaming is used on form and fill machines.

[0036] The film surface activation treatment can be any suitable treatment method, such as plasma, flame, corona discharge, UV irradiation, electron beam irradiation, gamma irradiation, and the like. The film surface also can be treated chemically by subjecting the surface to oxidizing or etching agents. A preferred treatment is corona discharge as disclosed in U.S. Provisional Patent Application Ser. No. 60/454,444, filed Mar. 13, 2003 and in a U.S. patent application entitled “A Film Having a Liquid Absorbed Therein,” filed on Mar. 11, 2004, and incorporated herein by reference.

[0037] It is known to treat a polyolefin material by corona discharge to improve the wetability of the polyolefin surface. Typically the polyolefin is treated to increase the surface energy from about 30-32 dynes up to about 37-40 dynes. The power levels required to provide such increases in dyne level depend to some extent on the nature of the material to be treated and any additives therein, because different materials can respond differently. For example, polyesters require relatively low power levels of about 8 to 11 W-m/M², whereas polypropylene requires relatively high power levels of about 22 to about 27 W-m/M². Higher corona treatment levels are considered undesirable because it is believed a breakdown of the polymer surface occurs and low molecular weight products are released, which reduces the ability of the film surface to bond.

[0038] It also is known to treat a polyolefin layer that forms an interior surface of a tubular food casing by corona discharge. The corona discharge treatment improves the meat adhesion properties of the film surface. Typically, polyethylene is treated such that the surface energy of the film is increased to about 40 to about 50 dynes. A certain degree of adhesion to meat is desirable to avoid a collection of juices between the meat and film package. Such a condition is known as “cookout” or purge. However, excessive adhesion is undesirable because the film does not release cleanly from the meat surface, and a portion of the meat is pulled away with the film. This results in a scarred and unsightly meat appearance.

[0039] Corona treatment of the interior surface of a tubular casing is described in U.S. Pat. No. 5,296,170, incorporated herein by reference. Polyamide casing materials, which have a surface energy of up to about 45 dynes, generally have sufficient meat adhesion properties and corona treatment is not required. It is believed that if a polyamide is corona treated, then the resulting film would adhere excessively to a meat surface, causing the abovementioned problems.

[0040] The level of surface activation to which a film surface is subjected varies depending upon the identity of the film and the particular surface activation treatment. The level of surface activation necessary for a particular substrate can be determined by a person of skill in the art by simple experimentation. Preferably, the surface is activated to a sufficient degree to retain a composition of the present invention in an amount of about 0.1 to about 1.5, and preferably about 0.2 to about 1.3 mg/cm². To achieve the full advantage of the present invention, the film surface is activated to a sufficient degree to retain a composition of the present invention in an amount of about 0.3 to about 1.2 mg/cm² (milligrams of composition per square centimeter of film surface).

[0041] It should be understood that it is not necessary to activate the film surface before application of a present composition. A present composition can be applied directly to an unactivated film. Persons skilled in the art are aware of the amount of present composition, i.e., about 0.1 to about 1.5 mg/cm², to apply to an unactivated film for retention, then transfer, of a browning agent to an encased food product.

[0042] A present liquid coating composition comprises (a) a browning agent, (b) a viscosity-modifying agent, (c) an optional surfactant and/or a polyol, (d) an optional salt, and (e) water, and has a pH of about 2 to about 6.5. The composition also optionally comprises a flavoring agent. The composition further can contain additional optional ingredients, such as a binder or gelling agent.

[0043] Preferably, for cook-in purposes, the browning agent is a type that reacts with foodstuff proteins by a Maillard reaction and produces a brown color characteristic of smoked meat. Browning agents that react with proteins in this manner are active carbonyl compounds, such as, but not limited to, aldehydes, e.g., hydroxyacetaldehyde, and reducing sugars, such as fructose, glucose, ribose, lactose, xylose, and the like. A browning agent that is particularly useful is hydroxyacetaldehyde.

[0044] Preferred browning agents are liquid coloring agents available under the tradename MAILLOSE® from Red Arrow Products Co. LLC, Manitowoc, Wis. MAILLOSE® contains hydroxyacetaldehyde, and is prepared from the pyrolysis of sugars and starches. Traditional liquid smoke products also are useful in a composition of the present invention. Liquid smoke is a collection of condensable products from the pyrolysis of wood or cellulose. Liquid smoke includes active carbonyl compounds as browning agents and further contains flavoring agents, e.g., phenols and acids. Liquid smoke is available under the tradename CHARSOL®, from Red Arrow Products Co. LLC.

[0045] Preferred browning agents comprise a relatively concentrated amount of hydroxyacetaldehyde. Especially preferred is a browning agent comprising about 20 to about 47 wt %, preferably about 25 to about 40 wt %, and most preferably about 30 to about 35 wt %, hydroxyacetaldehyde.

[0046] Other optional browning agents unrelated to the pyrolysis of wood, cellulose, and starches can be used in addition to hydroxyacetaldehyde and a liquid smoke browning agent. These browning agents act as dyes to impart additional color to the cooked foodstuff. Such optional browning agents are well known in the art and include, but are not limited to, caramel, beet extract, malt, bixin, annatto, and mixtures thereof.

[0047] A present composition also includes at least one viscosity-modifying agent. Viscosity-modifying agents suitable for use in contact with food are well known in the art and include materials such as cellulosics and gums, like cellulose, methylcellulose, hydroxypropylcellulose, starch, chitin, carrageenan, konjac, guar gum, xanthan gum, alginic acid and derivatives thereof, agar, pectin, gelatin, and the like.

[0048] Preferred viscosity-modifying agents comprise a water-soluble cellulose ether including, but not limited to, methylcellulose, hydroxypropylmethylcellulose, hydroxypropylcellulose, ethyl methylcellulose, hydroxyethylcellulose, and ethyl hydroxyethylcellulose. More preferably, the viscosity-modifying agent comprises an anionic water-soluble cellulose ether including, but not limited to, carboxymethylcellulose and carboxymethyl hydroxyethylcellulose. Mixtures of water-soluble cellulose ethers also can be employed. Particularly preferred viscosity-modifying agents are the methylcellulose ethers sold under the tradename METHOCEL®.

[0049] Typically, a present composition includes up to about 2 wt %, preferably up to about 1 wt % of a viscosity-modifying agent. A more preferred composition includes about 0.05 to about 0.5 wt %, and most preferably about 0.10 and 0.25 wt %, of a viscosity-modifying agent.

[0050] A present composition optionally further includes one or more surfactant and/or polyol. Suitable surfactants are anionic and nonionic surfactants, including, but not limited to, calcium stearoyl lactylate, a diglyceride, dioctyl sodium sulfosuccinate, lecithin, a monoglycerides, polysorbate 60, polysorbate 65, polysorbate 80, sodium lauryl sulfate, sodium stearoyl lactylate, sorbitan monostearate, or a mixture thereof. A preferred polyol is propylene glycol, glycerol, or a mixture thereof.

[0051] The surfactant, glycol, or mixture thereof, in total, is present in the composition in an amount of up to about 10 wt %, and preferably about 0.5 to about 8 wt %. To achieve the full advantage of the present invention the total amount of surfactant, glycol, or mixture thereof present in the composition is about 1 to about 5 wt %.

[0052] A present composition also optionally includes a pharmaceutically acceptable salt, e.g., sodium chloride, in a sufficient amount to approximate the salt content of a foodstuff encased in the casing. A salt typically is present in the composition in an amount of 0 to about 3 wt %, and preferably about 0.5 to about 2.5 wt %. To achieve the full advantage of the present invention, the composition contains about 1 to about 2 wt % of a salt.

[0053] It is theorized, but not relied upon herein, that the salt, in some instances, helps mitigate deep migration of the composition from the casing into the interior of the encased foodstuff. In the overall composition, it is important that the composition does not migrate deeply into the encased foodstuff. By retarding migration of the composition into the encased foodstuff, the browning agent remains at or in the vicinity of the surface of the foodstuff and thereby provides a maximum brown color to the cooked or heated foodstuff.

[0054] A composition of the present invention is aqueous, and has a pH of about 2 to about 6.5, and preferably about 3 to about 6.5. To achieve the full advantage of the present invention, the composition has a pH of about 4 to about 6. The composition pH therefore approximates the pH of the encased foodstuff, and reduces the problem of “purge” during cooking or heating.

[0055] Therefore, an important feature of the present invention is to provide a composition for application to a surface of a cook-in film comprising about 20 to about 40 wt % of a browning agent, preferably hydroxyacetaldehyde, up to about 2 wt % of a viscosity-modifying agent, optionally up to about 10 wt % of a surfactant, glycol, or mixture thereof, optionally up to about 3 wt % of a salt, and having a pH of about 2 to about 6.5.

[0056] An especially preferred composition includes about 20 to about 40 wt % hydroxyacetaldehyde in combination with a methylcellulose and a polyol, such as propylene glycol, preferably up to about 10 wt %, more preferably up to about 5 wt %, polyol. A preferred composition also contains up to about 1.5 wt % of a salt, and a pH of about 4 to about 6.

[0057] The composition optionally also can indude other ingredients, such as, but not limited to, antimicrobial agents, antioxidants, and stabilizers. An optional ingredient included in the composition is present in a sufficient amount to perform its intended function without adversely affecting the composition, film, or foodstuff.

[0058] The specific identity and amount of the individual components of the present composition are judiciously selected after considering the nature of the surface, the material of construction of the film, and the specific foodstuff to be packaged. Consideration also is given to a desirable color or flavor profile of different meat products with a view to consumer acceptance.

[0059] The level and rate of transfer of composition components from the film to the foodstuff can be influenced by the hydrophilic/lipophilic nature of the film surface, the specific composition, and the foodstuff. While not being bound by any theory, it is theorized that transfer of hydrophilic composition materials, e.g., browning agents, to a foodstuff having a relatively high water content (e.g., whole muscle products, like hams) is facilitated compared to a foodstuff having a relatively high fat content (e.g., some types of sausages). It also is theorized that composition transfer can be modified by the relative adhesion and retention of the composition to and in the film, and the absorbency of the composition into the foodstuff. For example, the present composition can be admixed with an edible oil prior to application to the film to reduce adhesion and improve absorbency.

[0060] A present composition can be applied to a surface of the film by any suitable technique. One suitable, nonlimiting, process for applying a composition to a tubular casing is described in U.S. Pat. No. 3,378,379, incorporated herein by reference. This process is known in the casing art as slugging. The slugging method for application of a composition to the inside of a casing involves filling a portion of the casing with the coating material, such that the slug or coating material generally resides at the bottom of a “U” shape formed by the casing, and then moving a continuous, indefinite length of casing such that the slug of coating material remains confined within the casing, while the casing moves past the slug and a present coating composition contained within the slug is applied to its inside wall.

[0061] A modified slugging process also can be used to apply a present composition to film surface, wherein the slug is trapped between upper and lower pair of nip rolls. The upper set of rolls preferably includes a chrome roller and a rubber roller. The rubber roller typically has a hardness of between about 60 to about 120, typically between about 70 to about 100, durometer. As the tube passes between the two sets of rollers, the composition is carried with the film and the upper set of rolls act as metering rolls.

[0062] Preferably the gap between the roller is set at less than the thickness of the film, typically at about 50%. This is in contrast to conventional application techniques where the gap is set equal to the film thickness plus the desired thickness of the coating layer. While not wishing to be bound by theory, it is believed that the pressure created as the film passes between the rollers assists in forcing the composition into the walls of the film. Typical levels of absorption are in the order of about 20 to about 28% by weight.

[0063] Food casings comprising a film coated with a composition of the present invention can be in any form known in the art, such as in the form of shirred casing sticks, discrete short segments of flattened casings, continuous lengths of flattened casing on a reel, and the like.

[0064] When the film is in the form of a tubular casing, the tube typically is shirred after application of the present coating composition. Shirring can be accomplished by conventional shirring techniques well known to persons skilled in the art.

[0065] Another important feature of the present invention is to provide a shirred tubular food casing having an interior food contact surface having a liquid composition of the present invention applied thereto for transfer to a foodstuff encased therein. Prior to application of the composition to the surface., the surface preferably is subjected to a surface activation treatment.

[0066] After a present composition is applied to the film, the film can be used as a casing for a food product. When the film is in the form of a tubular casing or a shirred casing, the casing can be stuffed by pushing a meat product through a stuffing horn into the inside of the tubular casing.

[0067] Another important feature of the invention is to provide a method of processing, e.g., cooking or heating, a food product comprising packaging a foodstuff within a film treated with a composition of the present invention, then heating the packaged foodstuff for a sufficient time and at a sufficient temperature for components of the composition to transfer to a surface of the foodstuff and impart a brown color to the foodstuff.

[0068] As demonstrated hereafter, it is preferred that a foodstuff is heated or cooked as soon as possible after encasing the foodstuff in a film having a present composition applied thereto. It has been found that browning of the cooked or heated foodstuff is maximized when the encased foodstuff is cooked or heated as soon as practical after encasing.

[0069] A foodstuff packaged within the film can be cooked by any suitable method, such as boiling, heating by steam, or in an oven. Preferably, the packaged foodstuff is cooked as soon as practical after packaging. As illustrated hereafter, the brown color imparted to the foodstuff is optimized when the encased foodstuff is processed within four hours, preferably within two hours, and more preferably within one to one and one-half hours after packaging. Processing shortly after packaging fixes the browning agents at or near the surface of the foodstuff, and foodstuff browning is not diminished because of browning agent migration deeper into the foodstuff.

[0070] Alternatively, the food product can be subjected to a preheating step to transfer the components of the composition to the foodstuff and fix the color prior to cooking. For example, the packaged foodstuff can be preheated to a temperature of about 150° F. to about 200° F. for a period of up to about 6 minutes. During cooking or preheating, the browning agent of the present composition imparts an esthetic color to the surface of the food.

EXAMPLE 1 Coating Compositions

[0071] Coating compositions of the present invention were prepared according to Table 1 by admixing composition components. TABLE 1 Composition Meat and Cooking No. Composition (wt %) Variables C_(3/02) MAILLOSE ® 45¹⁾ 94.63 Uniform surface Propylene Glygol 5.00 color. No purge. Dioctyl Sulfosuccinate 0.25 ΔL = 7.7 Xanthan Gum 0.12 C₁ MAILLOSE ® 45¹⁾ 94.50 Uniform surface Propylene Glygol 5.00 color. No purge. Dioctyl Sulfosuccinate 0.25 ΔL = 9.9 Xanthan Gum 0.25 C₂ MAILLOSE ® 45¹⁾ 94.50 Purge heavy when Propylene Glygol 5.00 product held Dioctyl Sulfosuccinate 0.25 prior to proces- Xanthan Gum 0.25 sing. Color splotchy. C₃ WFE²⁾ 94.00 Purge heavy when Propylene Glycol 5.00 product held Xanthan Gum 0.30 prior to proces- Konjac Gum 0.20 sing. Color METHOCEL ® E-15 0.50 splotchy. C_(x) WFE²⁾ 94.75 Slight purge when Propylene Glycol 5.00 product held Dioctyl Sulfosuccinate 0.25 prior to proces- sing. ΔL = 7.88 C₄ WFE 94.875 Very splotchy Propylene Glycol 5.000 color. Xanthan Gum 0.125 C₅ WFE 94.875 Very splotchy Caramel Color 5.000 color. Propylene Glycol 5.000 Xanthan Gum 0.125 C₆ MAILLOSE ® 45 94.75 Heavy gelatinous Propylene Glycol 5.00 purge. METHOCEL ® SG A16M 0.25 C₇ MAILLOSE ® 45 94.875 Uniform surface Propylene Glycol 5.000 color. Dry sur- METHOCEL ® SG A16M 0.125 face. ΔL = 13.9 C₈ WFE 94.75 Heavy gelatinous Propylene Glycol 5.00 purge. METHOCEL ® A16M 0.25 C₉ WFE 94.875 Uniform color. Propylene Glycol 5.000 Dry surface. METHOCEL ® SG A16M 0.125 ΔL = 19.1 C₁₀ WFE 94.94 Uniform color. Propylene Glycol 5.00 Dry surface. METHOCEL ® SG A16M 0.06 ΔL = 5.65 C₁₁ R26 RTP³⁾ 94.875 Uniform color. Propylene Glycol 5.000 Dry surface. METHOCEL ® SG A16M 0.125 C₁₂ WFE 84.875 Uniform color. Caramel 10.000 Dry surface. Propylene Glycol 5.000 Caramel added for METHOCEL ® SG A16M 0.125 staining power to darken. C₁₃ RA 9751⁴⁾ 94.875 Dry surface. Propylene Glycol 5.000 Very splotchy pH METHOCEL ® SG A16M 0.125 12.5 liquid smoke for staining/- color develop- ment. C₁₄ WFE 97.375 Uniform surface Propylene Glycol 2.500 color. Dry METHOCEL ® SG A16M 0.125 surface. ΔL = 6.34 C₁₅ WFE 92.44 Splotchy color. Propylene Glycol 7.50 Surface dry. METHOCEL ® SG A16M 0.06 C₁₆ WFE 92.44 Splotchy color. Glycerol 7.50 Surface dry. METHOCEL ® SG A16M 0.06 C₁₇ WFE 94.875 Glycerol 5.000 METHOCEL ® SG A7C 0.125 C₁₈ WFE (42% HA) 94.875 Dark, dull brown. Propylene Glycol 5.000 Dry surface. METHOCEL ® SG A16M 0.125 Splotchy. Vis- cosity too high to uniformly coat. C₁₉ WFE (47% HA) 94.875 Propylene Glycol 5.000 METHOCEL ® SC A16M 0.125 C₂₀ MAILLOSE ® 45 98.4 Uniform mahogany Propylene Glycol 1.4 color. Dry METHOCEL ® K 100M 0.2 surface. C₂₁ WFE 98.4 Uniform mahogany Propylene Glycol 1.4 color. Dry METHOCEL ® K 100M 0.2 surface. C₂₂ WFE (42% HA) 100.0 Uniform brown color. Dry sur- face. Casing splotchy. Vis- cosity too high. C₂₃ MAILLOSE ® 45 99.75 Xanthan Gum .25 C₂₄ WFE (70 Brix) 94.8 Propylene Glycol 5.0 METHOCEL ® K 100M 0.2 C₂₅ WFE (70 Brix) 94.875 Splotchy, no Propylene Glycol 5.000 purge, ΔL = 12.51 METHOCEL ® SG A16M 0.125 C₂₆ MAILLOSE ® 45 97.20 METHOCEL ® K100M 0.35 Propylene Glycol 2.45 C₂₇ WFE²⁾ 94.875 Splotchy, some METHOCEL ® SG A16M 0.125 purge, ΔL = 14.41 Propylene Glycol 5.0 C₂₈ WFE²⁾ 94.814 Uniform color, no METHOCEL ® SG A16M 0.186 purge, good Propylene Glycol 5.0 casing to meat adhesion, ΔL = 10.63 C₂₉ WFE²⁾ 94.78 Splotchy, slight METHOCEL ® SG A16M 0.22 purge, ΔL = 13.35 Propylene Glycol 5.0 C₃₀ WFE²⁾ 94.875 Very splotchy, METHOCEL ® K 100M 0.125 excess purge, Propylene Glycol 5.0 ΔL = 14.12 C₃₁ WFE²⁾ 94.814 Uniform color, METHOCEL ® K 100M 0.186 slight purge, Propylene Glycol 5.0 ΔL = 11.76 C₃₂ WFE²⁾ 94.78 Very splotchy, METHOCEL ® K 100M 0.22 excess purge, Propylene Glycol 5.0 ΔL = 14.94 C₃₃ WFE²⁾ 94.625 Uniform color, METHOCEL ® SG A16M 0.125 slight purge, Dioctyl Sulfosuccinate 0.250 ΔL = 11.23 Propylene Glycol 5.000 C₃₄ MAILLOSE§ 45 94.875 Slightly Propylene Glycol 5.000 splotchy, good METHOCEL ® SG A16M 0.125 casing to meat adhesion, ΔL = 17.01 C₃₅ WFE²⁾ 92.875 Very splotchy, Propylene Glycol 5.000 purge moderate, Sodium Chloride 2.000 ΔL = 11.06 METHOCEL ® SG A16M 0.125 C₃₆ WFE²⁾ 94.75 Difficult to Propylene Glycol 5.00 shirr. Slightly Dioctyl Sulfosuccinate 0.25 splotchy, no purge. AL = 11.41 C₃₇ WFE (pH 5.5)²⁾ 94.875 Splotchy surface, Propylene Glycol 5.000 no purge, METHOCEL ® SG A16M 0.125 ΔL = 12.37 C₃₈ WFE (70 Brix) 94.625 Propylene Glycol 5.000 Dioctyl Sulfosuccinate 0.250 METHOCEL ® SG A16M 0.125 C₃₉ MAILLOSE ® 45 94.625 Propylene Glycol 5.000 Dioctyl Sulfosuccinate 0.25 METHOCEL ® SG A16M 0.125

[0072] A preferred composition contains about 90 to 97 wt % WFE or MAILLOSE® (65 brix) for maximum browning and optimum solids, about 5 wt % propylene glycol for METHOCEL® hydration and ease of peeling, about 0.125 wt % SG A16M METHOCEL® for water binding, viscosity control, and surface tension control, about 2 wt % sodium chloride to normalize the composition with meat-free water and thereby minimize composition/color migration and to reduce METHOCEL gel temp, and pH 5 by the addition of a sufficient amount of sodium hydroxide (NaOH) or phosphate to minimize protein syneresis and purge.

EXAMPLE 2 Corona Treatment of a Polyamide Film

[0073] The following tests were performed on a three-layer heat-shrinkable tubular film having an outer polyamide layer, an intermediate polypropylene copolymer layer, and an inner polyamide layer. The inner layers were subjected to a pretreatment to provide an irregular surface morphology.

[0074] The tubular film was internally corona treated at 600 watt 13.6 kilovolt using an electrode apparatus similar to that described in U.S. Pat. No. 5,296,170, wherein one of a pair of electrodes is placed in contact with one side of an inflated tube. In this way, a corona discharge is generated in the air space within the tube. However, a significant difference between the method described in U.S. Pat. No. 5,296,170 is that in the present example, much higher power levels are used. Although U.S. Pat. No. 5,296,170 does not disclose the power level in watt density, the examples show an increase in dyne level of a polyethylene film from 31 dyne to 42 and 41 dyne. However, it can be estimated from this change in dyne level that the power level is about 18 and 23 watt. In order to provide for the significant increase in power level for the present process, two electrode treater stations were mounted in series. The total power was split equally between the two stations.

[0075] After corona treatment, the interior surface of the film was coated by slugging as described in U.S. Pat. No. 3,378,379 and summarized below:

[0076] 1. The tube is slit open and an amount or “slug” of the coating is added;

[0077] 2. Air is injected to form the tube into a cylindrical shape and the slit is sealed with a tape;

[0078] 3. The tube is advanced through, and partially collapsed through, a set of coating rolls. The spacing between the coating rolls is adjustable such that the rolls are not totally closed. As the film with the coating passes through the rolls; most of the liquid is squeezed out; and

[0079] 4. The film with the coating on the inside surface is then wound into reels.

[0080] Three coating trials were conducted with varying levels of corona treatment followed by coating under identical conditions of speed, nip roll gap, and nip roll structure. The level of surface activation was estimated by measuring the surface energy in dynes. The results are summarized in Table 2. The composition used was Composition No. C₁, the components of which are set forth in Table 1. TABLE 2 Line Corona Dyne Speed Add-on¹⁾ Treatment Level W-min/cm² (fpm) mg/cm² Increase % No 52 0 45 0.40 0 Yes 58 78 45 0.46 15 Yes 66-70 228 45 0.67 67.5

[0081] The results summarized in Table 2 show a 67% increase in the amount of composition that can be absorbed into the inner layer of the casing, and the amount of coating composition retained on the inner surface of the film directly correlates to the level of corona treatment, as measured in dynes.

[0082] The dyne levels in Table 2 are well in excess of that achieved by corona treatment used to facilitate meat adhesion, i.e., between 40 to 50 dynes provide acceptable meat adhesion. It is generally accepted in the art: that if films are treated to a dyne level above about 50 dynes, then the film unduly adheres to the meat surface. In the present invention, it was surprisingly observed that despite these high levels of surface activation, the composition-treated film unexpectedly released cleanly from the meat surface without meat scarring.

[0083] In the experiments it was observed that the surface activation was sufficiently high such that the dyne level was outside of the usual dyne measurement techniques. For this reason, the level of surface activation was estimated in terms of watt density.

[0084] Watt density is calculated according to the following formula: ${{Watt}\quad {density}} = \frac{{power}\quad {supple}\quad ({watts})}{{tube}\quad {width}\quad (M) \times 2 \times {line}\quad {speed}\quad \left( {\min \text{/}M} \right)}$

[0085] The width of tube was multiplied by two to account for the fact that the tube is double sided. Such a correction would not be necessary for a single sheet film.

[0086] To further demonstrate the amount of composition that can be absorbed into a polyamide film is a function of the corona treatment, the film used in the tests of Table 1 was treated at two different corona levels. Moisture then was applied to the film and the amount of moisture absorbed was determined per ASTM 570. This test requires specimens to be conditioned in an oven for 24 hours at 50° C. cooled in a desiccator, then immediately weighed to the nearest 0.001 g. After conditioning, the test specimens were immersed in distilled water that was maintained at room temperature (23° C.±1C°) for 72 hours. At the end of the test, the specimens were removed from the water, all surface water was wiped off with a dry cloth, then the specimen was weighed immediately to the nearest 0.0001 g.

[0087] To calculate the percentage increase in weight during immersion, the following equation was used: ${{Increase}\quad {in}\quad {weight}},{\% = {\frac{\left( {{{Wet}\quad {weight}} - {{Initial}\quad {weight}}} \right)}{{Initial}\quad {weight}} \times 100}}$

[0088] Table 3 summarizes the results of the test. The results indicate that the amount of moisture that is absorbed increases as the corona level is increased. TABLE 3 Test % Weight Gain W-m/M² 1 no corona 12.9 — 2 14.7 About 75 3¹⁾ 18.7 189.3

[0089] To demonstrate that a present composition is absorbed when applied to the inner surface of the film, the following test was devised:

[0090] Film samples were cut to fit circular hoops similar to those used to hold cloth when doing needle point. The inner surface of the film was placed in the hoop so that the rim of the hoop and the film formed a container. Before the film was clamped into the hoop the thickness of each film specimen was measured to the nearest 0.0001 in using a linear gauge. All test specimens were conditioned in an oven for 24 hours at 50° C. and cooled in a desiccator. The film specimens then were clamped into the hoops.

[0091] A solution containing MAILLOSE® (C20) was added to the inner surface of a film of the structure polyamide/tie/polyamide. This film is referred to here after as V9. The MAILLOSE® solution was added to just cover the surface of the film. This method insures that only the inner surface of the film has solution applied, and closely simulates the slugging process.

[0092] Excess MAILLOSE® solution was poured from the hoop, the specimens were removed from the hoop, then all surface solution was wiped off with a dry cloth. The specimen was cut into 3 pieces, then weighed immediately to the nearest 0.0001 g. All film specimens were then reconditioned for the same time and temperature as used in the original drying period (24 hours at 50° C.) and weighed to the nearest 0.0001 g.

[0093] Table 4 summarizes the results obtained for this test. It can be seen that the amount of composition add-on increased with an increase corona treatment. These results show that the corona treatment, as measured in watts per minute per m², considerably increases the level of coating composition that can be applied to the film. TABLE 4 Treatment Material w-min/m² Absorption % V9-control 0 23.9 V9-50 50 28.6 V9-100 100 30.4 V9-150 150 37.0 V9-200 200 33.1 V9-250 250 32.2 V9-300 300 30.6 V9-400 400 30.1 V9-500 500 31.4

EXAMPLE 3 Shirring, Stuffing, and Processing

[0094] Films were coated with the above coatings as described in Example 2. The coated films, after allowing time for the coating to adhere and/or be absorbed onto the rolls, were shirred into “sticks.” Shirred tubular casings are prepared by conventional shirring machines known in the art. Ham or turkey meat products then are pushed through a stuffing horn into the shirred casings.

[0095] The encased food products then were cooked in an oven for a sufficient time for the food product to reach an internal temperature of 160° F. The oven was maintained at 100% relative humidity and a temperature of 185° F. Cooking was conducted as soon as practicable after stuffing. Controls were conducted in the absence of corona treatment and coating.

[0096] The results are summarized in Table 5. TABLE 5 Inner Coating Treatment Add-on Product Colorimetric Values Layer Type Colorant W-min/m² mg/cm² Type L a b ΔL LLDPE None None None None Turkey 71.43 5.70 8.80 — Nylon C₉ Liquid 205.8 .94 Turkey 56.55 11.47 22.40 14.88 Smoke LLDPE None None None None Ham 65.35 12.02 9.72 — Nylon C₉ Liquid 169.8 .90-1.00 Ham 50.36 14.91 23.70 14.99 Smoke LLDPE None None None None Ham 65.69 11.86 5.59 — Nylon C MAILLOSE ® 196 .42 Ham 62.45 11.86 19.84  3.24 Nylon C₆ MAILLOSE ®  61.2 .56 Ham 59.01 12.90 21.26  6.68 LLDPE None None None None Turkey 74.14 5.19 8.32 — Nylon C MAILLOSE ® 196 .42 Turkey 69.49 9.78 27.35  4.65 Nylon C₆ MAILLOSE ®  61.2 .56 Turkey 62.40 10.93 27.02 11.74 LLDPE None None None None Turkey 75.1 N/A N/A — LLDPE C MAILLOSE ® 300 .42 Turkey 73.4 N/A N/A 1.7 Nylon C MAILLOSE ® 300 .42 Turkey 67.4 N/A N/A 7.7

[0097] Both the ham and turkey products cooked in the treated film have a uniform, smoked brown color. The uniform color of the foodstuff indicates that a composition of the present invention is uniformly coated on the film, and that this uniform coating is resistant to disruption by shirring and stuffing procedures. A composition of the present invention also has sufficient flexibility to stretch during stuffing and shrink during heat-shrinkage of the film. Still further, there is no evidence of purge or cook-out, or an unacceptable adhesion of the film to the foodstuff.

[0098] Accordingly, a surface treated film can retain a composition of the present invention in a significantly greater amount than an untreated film. Further, a surface treated film can be shirred and stuffed by conventional shirring and stuffing procedures.

EXAMPLE 4

[0099] Tests were performed to demonstrate that a composition of the present invention, after application to a corona-treated casing, retards migration of the browning composition into an encased foodstuff. In particular, compositions C₂₅ through C₃₇, and a control, individually, were applied to a corona-treated casing. Then, the casing was stuffed with chunked and formed ham using a Tipper RS4202 apparatus. The resulting foodstuffs were metal molded and hot water cooked at 165° F. The results in Table 6 illustrate that a present composition remains at or in the vicinity of the surface of a cooked foodstuff, thereby maximizing the brown color of the foodstuff surface. TABLE 6 Composition Penetration (mm) C₂₅ 2 C₂₇ 2 C₂₈ 1.5 C₃₁ 1.5 C₃₄ 1.5 C₃₅ 1 C₃₆ 2 C₃₇ 2-3

EXAMPLE 5

[0100] Tests also were performed to demonstrate that cooking immediately after stuffing provides a deeper, more esthetic golden brown color. A foodstuff was encased in a corona discharge treated casing as set forth below. The treated casing had a composition of the present invention applied thereto.

[0101] The encased food products were cooked by heating in an oven, with steam or hot water, set for a length of time for the product to reach an internal temperature of 160° F. The oven was maintained at 100% relative humidity and a temperature of 185° F. The steam and hot water temperatures are noted in the following table. Cooking was conducted either as soon as practicable or at various times after stuffing as noted. Inner Colorimetric Foodstuff Coating Layer L Value Comments Turkey None LLDPE 74.6 Product held (Control) before processing Turkey C_(3/02) Nylon 72.93 Processed after stuffing Turkey C_(3/02) LLDPE 73.97 Held 4.5 hours Turkey C Nylon 70.07 Processed immediately Turkey C Nylon 73.56 Held 4 hours Turkey C₁ Nylon 67.55 Processed immediately Turkey C₁ Nylon 73.26 Held 4 hours Turkey C_(x) Nylon 69.55 Processed immediately Turkey C_(x) Nylon 73.75 Held 4 hours Turkey C₂ Nylon 66.33 Processed immediately Turkey C₂ Nylon 61.48 Held 4 hours Turkey C₃ Nylon 66.57 Processed immediately Turkey C₃ Nylon 66.27 Held 4 hours Turkey C₁ Nylon 67.55 Processed immediately Turkey C₁ Nylon 73.26 Held 4 hours Turkey C₁ Nylon 61.67 Processed immediately Turkey C₁ Nylon 64.51 Held 4 hours

[0102] It will be appreciated that various changes and modifications may be made to the invention described herein without departing from the spirit and scope thereof. 

What is claimed is:
 1. A liquid composition for application to a food packaging film, said composition comprising: (a) about 20% to about 47%, by weight, of a browning agent; (b) about 0.05% to about 2%, by weight, of a viscosity-modifying agent; (c) 0% to about 10%, by weight, of a surfactant, a polyol, or mixture thereof; (d) 0% to about 3%, by weight, of a pharmaceutically acceptable salt; and (e) water, said composition having a pH of about. 2 to about 6.5 and capable of transferring the browning agent of the composition from the food packaging film to a foodstuff packaged in the food packaging film.
 2. The composition of claim 1 further comprising a flavoring agent.
 3. The composition of claim 1 wherein the composition comprises about 25% to about 40%, by weight, of the browning agent.
 4. The composition of claim 1 wherein the composition comprises about 30% to about 35%, by weight, of the browning agent.
 5. The composition of claim 1 wherein the browning agent is capable of undergoing a Maillard reaction with meat proteins.
 6. The composition of claim 1 wherein the browning agent comprises a pyrolysis product from combustion of a sugar, a starch, or a mixture thereof.
 7. The composition of claim 6 wherein the browning agent comprises aldehydes.
 8. The composition of claim 6 wherein the browning agent comprises hydroxyacetaldehyde.
 9. The composition of claim 1 wherein the browning agent comprises a pyrolysis product from combustion of wood or a cellulose.
 10. The composition of claim 2 wherein flavoring agent comprises a phenol, an acid, or a mixture thereof.
 11. The composition of claim 1 wherein the composition further comprises caramel, beet extract, malt, bixin, annatto, or a mixture thereof.
 12. The composition of claim 1 wherein the composition comprises about 0.05% to about 1%, by weight, of the viscosity-modifying agent.
 13. The composition of claim 1 wherein the composition comprises about 0.10% to about 0.25%, by weight, of the viscosity-modifying agent.
 14. The composition of claim 1 wherein the viscosity-modifying agent comprises a cellulosic or a gum.
 15. The composition of claim 1 wherein the viscosity-modifying agent comprises a cellulose ether.
 16. The composition of claim 15 wherein the viscosity-modifying agent comprises a water-soluble anionic cellulose ether.
 17. The composition of claim 1 wherein the viscosity-modifying agent is selected from the group consisting of cellulose, methylcellulose, hydroxypropylcellulose, starch, chitin, carrageenan, konjac, guar gum, xanthan gum, alginic acid and derivatives thereof, agar, pectin, gelatin, methylcellulose, hydroxypropylmethylcellulose, hydroxypropylcellulose, ethyl methylcellulose, hydroxyethylcellulose, ethyl hydroxyethylcellulose, carboxymethylcellulose, carboxymethyl hydroxyethylcellulose, and mixtures thereof.
 18. The composition of claim 1 wherein the composition comprises about 1% to about 8% of a surfactant, a polyol, or mixture thereof, by weight of the composition.
 19. The method of claim 1 wherein the composition comprises about 2% to about 5% of a surfactant, a polyol, or mixture thereof, by weight of the composition.
 20. The method of claim 1 wherein the composition comprises a surfactant.
 21. The method of claim 1 wherein the composition comprises a polyol.
 22. The method of claim 1 wherein the composition comprises a surfactant and a polyol.
 23. The method of claim 1 wherein the surfactant or glycol is selected from the group consisting of calcium stearoyl lactylate, a diglyceride, dioctyl sodium sulfosuccinate, lecithin, a monoglyceride, polysorbate 60, polysorbate 65, polysorbate 80, sodium lauryl sulfate, sodium stearoyl lactylate, sorbitan monostearate, propylene glycol, glycerol, and mixtures thereof.
 24. The composition of claim 1 wherein the browning agent comprises hydroxyacetaldehyde; the viscosity-modifying agent is selected from the group consisting of xanthan gum, konjac gum, a methylcellulose, and mixtures thereof; and the surfactant or glycol is selected from the group consisting of propylene glycol, dioctyl sulfosuccinate, glycerol, and mixtures thereof.
 25. The composition of claim 1 comprising about 0.5% to about 2.5%, by weight, of a salt.
 26. The composition of claim 1 comprising about 1% to about 2%, by weight, of a salt.
 27. The composition of claim 1 wherein the salt comprises sodium chloride.
 28. The composition of claim 1 having a pH of about 4 to about
 6. 29. A food packaging film having a composition of claim 1 applied to a food contact surface of the film.
 30. The film of claim 29 wherein the composition is applied to the food contact surface of the film in an amount of about 0.1 to about 1.5 milligrams of the composition per square centimeter of the food contact surface.
 31. A method of preparing and processing a foodstuff encased in a casing comprising the steps of: (a) providing a casing suitable for a foodstuff; (b) applying a composition of claim 1 to a surface of the casing that contacts a foodstuff; (c) stuffing a foodstuff into the casing of step (b); and (d) heating the stuffed casing of step (c) at a sufficient temperature and for a sufficient time to process the foodstuff.
 32. The method of claim 31 wherein heating step (d) is performed within four hours performing stuffing step (c). 